The demand for enantiomerically pure compounds has grown rapidly in recent years. One important use for such chiral, non-racemic compounds is as intermediates for synthesis in the pharmaceutical industry. For instance, it has become increasingly clear that enantiomerically pure drugs have many advantages over racemic drug mixtures. These advantages (reviewed in, e.g., Stinson, S. C., Chem Eng News, Sept. 28, 1992, pp. 46–79) include the fewer side effects and greater potency often associated with enantiomerically pure compounds.
Traditional methods of organic synthesis were often optimized for the production of racemic materials. The production of enantiomerically pure material has historically been achieved in one of two ways: use of enantiomerically pure starting materials derived from natural sources (the so-called “chiral pool”); and the resolution of racemic mixtures by classical techniques. Each of these methods has serious drawbacks, however. The chiral pool is limited to compounds found in nature, so only certain structures and configurations are readily available. Resolution of racemates, which requires the use of resolving agents, may be inconvenient and time-consuming. Furthermore, resolution often means that the undesired enantiomer is discarded, thus decreasing efficiency and wasting half of the material.